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          <h4 id="title">d3 Integration</h4>
          <div id="map" class="map"></div>

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          <p id="shortdesc">Example of using OpenLayers and d3 together.</p>
          <div id="docs"><p>The example loads TopoJSON geometries and uses d3 (<code>d3.geo.path</code>) to render these geometries to a canvas element that is then used as the image of an OpenLayers image layer.</p>
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          <div id="api-links">Related API documentation: <ul class="inline"><li><a href="../apidoc/ol.Map.html" title="API documentation for ol.Map">ol.Map</a></li>,<li><a href="../apidoc/ol.View.html" title="API documentation for ol.View">ol.View</a></li>,<li><a href="../apidoc/ol.extent.html" title="API documentation for ol.extent">ol.extent</a></li>,<li><a href="../apidoc/ol.layer.Image.html" title="API documentation for ol.layer.Image">ol.layer.Image</a></li>,<li><a href="../apidoc/ol.layer.Tile.html" title="API documentation for ol.layer.Tile">ol.layer.Tile</a></li>,<li><a href="../apidoc/ol.proj.html" title="API documentation for ol.proj">ol.proj</a></li>,<li><a href="../apidoc/ol.source.ImageCanvas.html" title="API documentation for ol.source.ImageCanvas">ol.source.ImageCanvas</a></li>,<li><a href="../apidoc/ol.source.Stamen.html" title="API documentation for ol.source.Stamen">ol.source.Stamen</a></li></ul></div>
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        <form method="POST" id="codepen-form" target="_blank" action="https://codepen.io/pen/define/">
          <textarea class="hidden" name="title">d3 Integration</textarea>
          <textarea class="hidden" name="description">Example of using OpenLayers and d3 together.</textarea>
          <textarea class="hidden" name="js">var map &#x3D; new ol.Map({
  layers: [
    new ol.layer.Tile({
      source: new ol.source.Stamen({
        layer: &#x27;watercolor&#x27;
      })
    })
  ],
  target: &#x27;map&#x27;,
  view: new ol.View({
    center: ol.proj.fromLonLat([-97, 38]),
    zoom: 4
  })
});


/**
 * Load the topojson data and create an ol.layer.Image for that data.
 */
d3.json(&#x27;https://openlayers.org/en/v4.6.5/examples/data/topojson/us.json&#x27;, function(error, us) {
  var features &#x3D; topojson.feature(us, us.objects.counties);

  /**
   * This function uses d3 to render the topojson features to a canvas.
   * @param {ol.Extent} extent Extent.
   * @param {number} resolution Resolution.
   * @param {number} pixelRatio Pixel ratio.
   * @param {ol.Size} size Size.
   * @param {ol.proj.Projection} projection Projection.
   * @return {HTMLCanvasElement} A canvas element.
   */
  var canvasFunction &#x3D; function(extent, resolution, pixelRatio,
      size, projection) {
    var canvasWidth &#x3D; size[0];
    var canvasHeight &#x3D; size[1];

    var canvas &#x3D; d3.select(document.createElement(&#x27;canvas&#x27;));
    canvas.attr(&#x27;width&#x27;, canvasWidth).attr(&#x27;height&#x27;, canvasHeight);

    var context &#x3D; canvas.node().getContext(&#x27;2d&#x27;);

    var d3Projection &#x3D; d3.geo.mercator().scale(1).translate([0, 0]);
    var d3Path &#x3D; d3.geo.path().projection(d3Projection);

    var pixelBounds &#x3D; d3Path.bounds(features);
    var pixelBoundsWidth &#x3D; pixelBounds[1][0] - pixelBounds[0][0];
    var pixelBoundsHeight &#x3D; pixelBounds[1][1] - pixelBounds[0][1];

    var geoBounds &#x3D; d3.geo.bounds(features);
    var geoBoundsLeftBottom &#x3D; ol.proj.transform(
        geoBounds[0], &#x27;EPSG:4326&#x27;, projection);
    var geoBoundsRightTop &#x3D; ol.proj.transform(
        geoBounds[1], &#x27;EPSG:4326&#x27;, projection);
    var geoBoundsWidth &#x3D; geoBoundsRightTop[0] - geoBoundsLeftBottom[0];
    if (geoBoundsWidth &lt; 0) {
      geoBoundsWidth +&#x3D; ol.extent.getWidth(projection.getExtent());
    }
    var geoBoundsHeight &#x3D; geoBoundsRightTop[1] - geoBoundsLeftBottom[1];

    var widthResolution &#x3D; geoBoundsWidth / pixelBoundsWidth;
    var heightResolution &#x3D; geoBoundsHeight / pixelBoundsHeight;
    var r &#x3D; Math.max(widthResolution, heightResolution);
    var scale &#x3D; r / (resolution / pixelRatio);

    var center &#x3D; ol.proj.transform(ol.extent.getCenter(extent),
        projection, &#x27;EPSG:4326&#x27;);
    d3Projection.scale(scale).center(center)
        .translate([canvasWidth / 2, canvasHeight / 2]);
    d3Path &#x3D; d3Path.projection(d3Projection).context(context);
    d3Path(features);
    context.stroke();

    return canvas[0][0];
  };

  var layer &#x3D; new ol.layer.Image({
    source: new ol.source.ImageCanvas({
      canvasFunction: canvasFunction,
      projection: &#x27;EPSG:3857&#x27;
    })
  });
  map.addLayer(layer);
});
</textarea>
          <textarea class="hidden" name="css"></textarea>
          <textarea class="hidden" name="html">&lt;div id&#x3D;&quot;map&quot; class&#x3D;&quot;map&quot;&gt;&lt;/div&gt;
</textarea>
          <input type="hidden" name="resources" value="https://openlayers.org/en/v4.6.5/css/ol.css,https://openlayers.org/en/v4.6.5/build/ol.js,https://d3js.org/d3.v3.min.js,https://d3js.org/topojson.v1.min.js">
          <input type="hidden" name="data">
        </form>
        <pre><code id="example-source" class="language-markup">&lt;!DOCTYPE html&gt;
&lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;d3 Integration&lt;/title&gt;
    &lt;link rel="stylesheet" href="https://openlayers.org/en/v4.6.5/css/ol.css" type="text/css"&gt;
    &lt;!-- The line below is only needed for old environments like Internet Explorer and Android 4.x --&gt;
    &lt;script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"&gt;&lt;/script&gt;
    &lt;script src="https://openlayers.org/en/v4.6.5/build/ol.js"&gt;&lt;/script&gt;
    &lt;script src&#x3D;&quot;https://d3js.org/d3.v3.min.js&quot;&gt;&lt;/script&gt;
    &lt;script src&#x3D;&quot;https://d3js.org/topojson.v1.min.js&quot;&gt;&lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;div id&#x3D;&quot;map&quot; class&#x3D;&quot;map&quot;&gt;&lt;/div&gt;
    &lt;script&gt;
      var map &#x3D; new ol.Map({
        layers: [
          new ol.layer.Tile({
            source: new ol.source.Stamen({
              layer: &#x27;watercolor&#x27;
            })
          })
        ],
        target: &#x27;map&#x27;,
        view: new ol.View({
          center: ol.proj.fromLonLat([-97, 38]),
          zoom: 4
        })
      });


      /**
       * Load the topojson data and create an ol.layer.Image for that data.
       */
      d3.json(&#x27;https://openlayers.org/en/v4.6.5/examples/data/topojson/us.json&#x27;, function(error, us) {
        var features &#x3D; topojson.feature(us, us.objects.counties);

        /**
         * This function uses d3 to render the topojson features to a canvas.
         * @param {ol.Extent} extent Extent.
         * @param {number} resolution Resolution.
         * @param {number} pixelRatio Pixel ratio.
         * @param {ol.Size} size Size.
         * @param {ol.proj.Projection} projection Projection.
         * @return {HTMLCanvasElement} A canvas element.
         */
        var canvasFunction &#x3D; function(extent, resolution, pixelRatio,
            size, projection) {
          var canvasWidth &#x3D; size[0];
          var canvasHeight &#x3D; size[1];

          var canvas &#x3D; d3.select(document.createElement(&#x27;canvas&#x27;));
          canvas.attr(&#x27;width&#x27;, canvasWidth).attr(&#x27;height&#x27;, canvasHeight);

          var context &#x3D; canvas.node().getContext(&#x27;2d&#x27;);

          var d3Projection &#x3D; d3.geo.mercator().scale(1).translate([0, 0]);
          var d3Path &#x3D; d3.geo.path().projection(d3Projection);

          var pixelBounds &#x3D; d3Path.bounds(features);
          var pixelBoundsWidth &#x3D; pixelBounds[1][0] - pixelBounds[0][0];
          var pixelBoundsHeight &#x3D; pixelBounds[1][1] - pixelBounds[0][1];

          var geoBounds &#x3D; d3.geo.bounds(features);
          var geoBoundsLeftBottom &#x3D; ol.proj.transform(
              geoBounds[0], &#x27;EPSG:4326&#x27;, projection);
          var geoBoundsRightTop &#x3D; ol.proj.transform(
              geoBounds[1], &#x27;EPSG:4326&#x27;, projection);
          var geoBoundsWidth &#x3D; geoBoundsRightTop[0] - geoBoundsLeftBottom[0];
          if (geoBoundsWidth &lt; 0) {
            geoBoundsWidth +&#x3D; ol.extent.getWidth(projection.getExtent());
          }
          var geoBoundsHeight &#x3D; geoBoundsRightTop[1] - geoBoundsLeftBottom[1];

          var widthResolution &#x3D; geoBoundsWidth / pixelBoundsWidth;
          var heightResolution &#x3D; geoBoundsHeight / pixelBoundsHeight;
          var r &#x3D; Math.max(widthResolution, heightResolution);
          var scale &#x3D; r / (resolution / pixelRatio);

          var center &#x3D; ol.proj.transform(ol.extent.getCenter(extent),
              projection, &#x27;EPSG:4326&#x27;);
          d3Projection.scale(scale).center(center)
              .translate([canvasWidth / 2, canvasHeight / 2]);
          d3Path &#x3D; d3Path.projection(d3Projection).context(context);
          d3Path(features);
          context.stroke();

          return canvas[0][0];
        };

        var layer &#x3D; new ol.layer.Image({
          source: new ol.source.ImageCanvas({
            canvasFunction: canvasFunction,
            projection: &#x27;EPSG:3857&#x27;
          })
        });
        map.addLayer(layer);
      });
    &lt;/script&gt;
  &lt;/body&gt;
&lt;/html&gt;</code></pre>
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